It works in vivo in cats and is already in active use, which should raise the odds of this working in vivo in humans by a lot.

True, cats seem to be wracked with viruses. I've had to feed mine acyclovir. I think cats may get antivirals more than humans do.

Based on typical pre-clinical to approval rates, 1 in 100 is on the optimistic side.

My favorite response to "in vitro" trials is that a 12ga shotgun is often 100% effective in vitro.